io.trino.sql.planner.iterative.rule.PruneApplySourceColumns Maven / Gradle / Ivy
/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.trino.sql.planner.iterative.rule;
import com.google.common.collect.ImmutableList;
import io.trino.matching.Captures;
import io.trino.matching.Pattern;
import io.trino.sql.planner.Symbol;
import io.trino.sql.planner.SymbolsExtractor;
import io.trino.sql.planner.iterative.Rule;
import io.trino.sql.planner.plan.ApplyNode;
import io.trino.sql.planner.plan.PlanNode;
import java.util.Optional;
import java.util.Set;
import static com.google.common.collect.ImmutableSet.toImmutableSet;
import static io.trino.sql.planner.iterative.rule.Util.restrictOutputs;
import static io.trino.sql.planner.plan.Patterns.applyNode;
/**
* This rule restricts outputs of ApplyNode's subquery to include only the symbols
* needed for subqueryAssignments. Symbols from the subquery are not produced at
* ApplyNode's output. They are only used for the assignments.
* Transforms:
*
* - Apply
* correlation: [corr_symbol]
* assignments:
* result_1 -> a in subquery_symbol_1,
* result_2 -> b > ALL subquery_symbol_2
* - Input (a, b, corr_symbol)
* - Subquery (subquery_symbol_1, subquery_symbol_2, subquery_symbol_3)
*
* Into:
*
* - Apply
* correlation: [corr_symbol]
* assignments:
* result_1 -> a in subquery_symbol_1,
* result_2 -> b > ALL subquery_symbol_2
* - Input (a, b, corr_symbol)
* - Project
* subquery_symbol_1 -> subquery_symbol_1
* subquery_symbol_2 -> subquery_symbol_2
* - Subquery (subquery_symbol_1, subquery_symbol_2, subquery_symbol_3)
*
* Note: ApplyNode's input symbols are produced on ApplyNode's output.
* They cannot be pruned without outer context.
*/
public class PruneApplySourceColumns
implements Rule
{
private static final Pattern PATTERN = applyNode();
@Override
public Pattern getPattern()
{
return PATTERN;
}
@Override
public Result apply(ApplyNode applyNode, Captures captures, Context context)
{
Set subqueryAssignmentsSymbols = applyNode.getSubqueryAssignments().getExpressions().stream()
.flatMap(expression -> SymbolsExtractor.extractUnique(expression).stream())
.collect(toImmutableSet());
Optional prunedSubquery = restrictOutputs(context.getIdAllocator(), applyNode.getSubquery(), subqueryAssignmentsSymbols);
return prunedSubquery.map(subquery -> applyNode.replaceChildren(ImmutableList.of(applyNode.getInput(), subquery)))
.map(Result::ofPlanNode)
.orElse(Result.empty());
}
}